Regs on a high Zs

[Booyaka]

its only a very small circuit, 2.5 twin and earth radial supplying two double sockets protected by a 16A MCB and a main RCD 30mA

 

[Spark123]

What is the R1+R2?

 

[Booyaka]

im going back there tomorrow to finish off some work and to do some more tests, what advice would you give just for me to have extra info to draw on

 

[Spark123]

It is seeming odd to me that a Zs is 3 ohms greater than Ze on a short circuit. Or were the measurements taken on different days with different weather conditions?

 

[Booyaka]

yeah i did find it bizarre because the run to the electrode is very short too just outside the outbuilding

 

[plugwash]

Is the outbuilding on a seperate electrode from the house? If so that would explain the radically different loop impedance values.

 

[Booyaka]

Yes, the House is TNCS an SWA cable feeds the outbuilding, only two core and the armouring is earthed from the house only and stops at the outbuilding, then an electrode is earthing the outbuilding

 

[Spark123]

A TN-CS with a Ze of 5 ohms is a problem!!

 

[Booyaka]

Yes, the House is TNCS an SWA cable feeds the outbuilding, only two core and the armouring is earthed from the house only and stops at the outbuilding, then an electrode is earthing the outbuilding

the outbuilding is TT

 

[securespark]

A TN-CS with a Ze of 5 ohms is a problem!!

Nods frantically in agreement...

 

[Booyaka]

yes but its TT that reads 5ohms, can people please read previous many many many thanks

 

[fireman22]

hang on, the armouring is earthed at the house end but not then used at the outbuilding? yes? why are you not using it???

 

[DESL]

Yes, the House is TNCS an SWA cable feeds the outbuilding, only two core and the armouring is earthed from the house only and stops at the outbuilding, then an electrode is earthing the outbuilding

I'm confused here what is the value of Ze at the house?

 

[DESL]

hang on, the armouring is earthed at the house end but not then used at the outbuilding? yes? why are you not using it???

We haven't got all the information here.

I think you have hit the nail on the head although I wouldn't like to export PME relying on armour for earthing rather use a 3rd core or seperate cpc.

 

[Booyaka]

guys i think there is a whole host of confusion going on, many thanks for peoples advice and direction